"Aqua" wrote in message ...
I don't like baking soda, either. I know, theoretically, carbonate is
carbonate...but baking soda seems to stress my fish, while calcium
carbonate
does not.

Where did you get CaCO3? Any online suppliers?

Buy finely ground aragonite, reef stores sell it. Get the finest grade
they have. Should be pretty cheap. The finer the better since it will
dissolve better this way.
You can get a chuck of limestone etc also but it'll take a few years
to dissolve that.
Aragonite has the same composition but a different structure that
dissolves a little bit easier than plain old calcite.

Often if the KH is low, so is the Ca.

Not sure about your black fern. I used baking soda and so have many
other folks with Java ferns, I have not seen what you speak of. Might
be something else in your tap water. Baking soda does have HCO3 and
Na, neither of which should cause a problem with Java fern which is
rather salt tolerant. CO3 is the same CO3 is the same CO3, doesn't
matter how you get it there. CO3 will simply shift to HCO3 at the
pH's/KH's we deal with.

Regards,
Tom Barr
Regards,
Tom Barr